1. Field of the Invention
The present invention relates to an optical transmission assembly, capable of monitoring emitted light with its simple construction.
2. Description of the Related Art
In an optical transmission assembly with a surface light emitting device mounted on an optical circuit substrate with a specified width core formed in cladding, the surface light emitting device, whose light emitting surface faces the core, is mounted on one side of the cladding, while a reflective surface is formed at a position in the core facing the light emitting surface of the surface light emitting device, and inclined in a longitudinal direction of the core. This allows light emitted from the surface light emitting device to be reflected at the reflective surface and passed to and transmitted in the core.
Also, in a light receiving side optical transmission assembly having a similar structure, a light receiving device, whose light receiving surface faces the core, is mounted on one side of the cladding, while a reflective surface is formed at a position in the core facing the light receiving surface of the light receiving device, and inclined in a longitudinal direction of the core. This allows light transmitted in the core to be reflected at the reflective surface and passed to the light receiving device.
With respect to the related art, see JP-A-2005-91460, JP-A-2006-292852, and JP-A-2003-227951.
Because surface light emitting LDs (laser diodes) such as VCSEL (vertical cavity surface emitting laser)-type LDs emits no backward light as in end face light emitting LDs such as Fabry-Perot LDs, it is impossible to realize its structure with a built-in monitor PD (photodiode) in an LD module. For this reason, VCSEL-type LDs stabilize emitted light intensity by, for example, keeping temperature constant without monitoring the emitted light intensity. However, adjusting temperature is difficult and temperature-adjusting apparatus is significantly power-consuming.
Although emitted light is considered to be forward-monitored by being branched by providing a branch, coupler, half mirror, etc. in the core, construction thereof is complicated, leading to an increase in cost and size of the optical transmission assembly.